Spinal correction system and method

ABSTRACT

A spinal correction apparatus comprises a body. A ratchet is disposed with the body. A longitudinal element is connected to the ratchet. A force is applied to at least a portion of the apparatus that causes dynamic incremental movement of the longitudinal element relative to the body in at least one direction. Methods of use are disclosed.

TECHNICAL FIELD

The present disclosure generally relates to medical devices for thetreatment of musculoskeletal disorders, and more particularly to asurgical system and method for correction of a spine disorder.

BACKGROUND

Spinal pathologies and disorders such as scoliosis and other curvatureabnormalities, kyphosis, degenerative disc disease, disc herniation,osteoporosis, spondylolisthesis, stenosis, tumor, and fracture mayresult from factors including trauma, disease and degenerativeconditions caused by injury and aging. Spinal disorders typically resultin symptoms including deformity, pain, nerve damage, and partial orcomplete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercisecan be effective, however, may fail to relieve the symptoms associatedwith these disorders. Surgical treatment of these spinal disordersincludes correction, fusion, fixation, discectomy, laminectomy andimplantable prosthetics. Correction treatments used for positioning andalignment may employ implants, such as rods or tethers, forstabilization of a treated section of a spine. This disclosure describesan improvement over these prior art technologies.

SUMMARY

Accordingly, a surgical system and method are provided. In oneembodiment, in accordance with the principles of the present disclosure,a spinal correction apparatus is provided. The spinal correctionapparatus comprises a body. A ratchet is disposed with the body. Alongitudinal element is connected to the ratchet. A force is applied toat least a portion of the apparatus that causes dynamic incrementalmovement of the longitudinal element relative to the body in at leastone direction.

In one embodiment, the spinal correction apparatus comprises an outersleeve extending between a first end and a second end. The outer sleeveincludes an inner surface that defines an elongated cavity. A ratchet isdisposed with the cavity of the outer sleeve. The ratchet comprises aninner sleeve including a first rack and a second rack formed on theinner surface of the outer sleeve. The ratchet further comprises acarriage, a first pawl engageable with the first rack and a second pawlengageable with the second rack. A rod is telescopically oriented withthe outer sleeve and connected to the carriage. The rod extends betweena first end and a second end. A rotatable cam is engageable with theinner sleeve in a configuration to facilitate incremental movement ofthe rod relative to the outer sleeve in a first axial direction. The camdefines a socket configured for engagement with an instrument. Anexpansion force is applied to the first end of the rod, which causesincremental movement of the rod, independent of the cam, relative to theouter sleeve in the first axial direction.

In one embodiment, the spinal correction apparatus comprises an outersleeve extending between a first end and a second end. The outer sleeveincludes an inner surface that defines an elongated cavity. A ratchet isdisposed with the cavity of the outer sleeve. The ratchet comprises adrive screw, a carriage and a helical pawl being engageable with thecarriage. A rod is telescopically oriented with the outer sleeve andconnected to the carriage. The rod extends between a first end and asecond end. A worm gear is engageable with the screw in a configurationto facilitate incremental movement of the rod relative to the outersleeve in a first axial direction and a second axial direction. The wormgear defines a socket configured for engagement with an instrument. Anexpansion force is applied to the first end of the rod, which causesincremental movement of the rod, independent of the worm gear, relativeto the outer sleeve in the first axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more readily apparent from thespecific description accompanied by the following drawings, in which:

FIG. 1 is a perspective view of one particular embodiment of a systemincluding a spinal correction apparatus in accordance with theprinciples of the present disclosure;

FIG. 2 is a perspective view of the components of the system shown inFIG. 1 with parts separated;

FIG. 3 is a perspective view of the system shown in FIG. 1;

FIG. 4 is a perspective break away view of the system shown in FIG. 1including a tool;

FIG. 5 is a perspective break away view of the system and tool shown inFIG. 4;

FIG. 6 is a perspective view of the system and tool shown in FIG. 5;

FIG. 7 is a perspective view of the system and tool shown in FIG. 5;

FIG. 8 is a cross sectional break away view of the system shown in FIG.1;

FIG. 9 is a cross sectional break away view of the system shown in FIG.1;

FIG. 10 is a cross sectional break away view of the system shown in FIG.1;

FIG. 11 is a perspective view of the system shown in FIG. 1;

FIG. 12 is a cross sectional break away view of the system shown in FIG.1;

FIG. 13 is a cross sectional break away view of the system shown in FIG.1;

FIG. 14 is a perspective view of the system shown in FIG. 1, disposedwith vertebrae;

FIG. 15 is a perspective view of the system and vertebrae shown in FIG.1;

FIG. 16 is a perspective view of one particular embodiment of a systemincluding a spinal correction apparatus in accordance with theprinciples of the present disclosure;

FIG. 17 is a perspective view of the components of the system shown inFIG. 16 with parts separated;

FIG. 18 is a perspective view of the system shown in FIG. 16;

FIG. 19 is a perspective break away view of the system shown in FIG. 16including a tool;

FIG. 20 is a perspective break away view of the system and tool shown inFIG. 19;

FIG. 21 is a perspective view of the system and tool shown in FIG. 19;

FIG. 22 is a perspective view of the system and tool shown in FIG. 19;

FIG. 23 is a perspective cutaway view of the system shown in FIG. 19;

FIG. 24 is a perspective cutaway view of the system shown in FIG. 19;

FIG. 25 is a perspective break away view of the system shown in FIG. 23;

FIG. 26 is a perspective view of the system shown in FIG. 16;

FIG. 27 is a cross sectional break away view of the system shown in FIG.16;

FIG. 28 is a cross sectional break away view of the system shown in FIG.16;

FIG. 29 is a cross sectional break away view of the system shown in FIG.16;

FIG. 30 is a perspective view of one particular embodiment of a systemincluding a spinal correction apparatus in accordance with theprinciples of the present disclosure;

FIG. 31 is a cross sectional break away view of the system shown in FIG.30;

FIG. 32 is a perspective view one particular embodiment of a systemincluding a spinal correction apparatus in accordance with theprinciples of the present disclosure; and

FIG. 33 is a perspective cutaway view of the system shown in FIG. 32.

Like reference numerals indicate similar parts throughout the figures.

DETAILED DESCRIPTION

The exemplary embodiments of the surgical system and related methods ofuse of the present disclosure are discussed in terms of medical devicesfor the treatment of musculoskeletal disorders and more particularly, interms of a spinal correction apparatus. It is envisioned that the spinalcorrection apparatus may be employed in applications for correction ofdeformities, such as, for example, kyphosis and scoliosis.

In one embodiment, the system includes a spinal correction apparatusthat provides a ratcheting extension with a back-up drive extension. Thesystem may comprise a minimal metal on metal design. The components ofthe system may comprise about a 4.5 inch (in) rod with about a 50millimeter (mm) extension or about a 5.5 in rod with about a 100 mmextension. The system can include a minimal overall length compared toextension length and can allow for extension and axial rotation. In oneembodiment, after implantation of the system in accordance with theprinciples of the present disclosure, a patient can be periodicallyplaced in traction in an effort to lengthen the rod and to compensatefor patient growth. In one embodiment, the rod automatically lengthensduring patient activity. In one embodiment, fluoroscopy can be used tolocate a drive hex of the system and a driver is percutaneously dockedand rotated in either direction to lengthen the system. It iscontemplated that components of the system may be coated with anantimicrobial agent to reduce the likelihood of infection.

In one embodiment, the spinal correction apparatus uses a cam to raiseand lower an inner sleeve during rotation and may be directionindependent. During upward motion of the inner sleeve, a carriage isengaged to a rack through the use of pawls. A pawl used in conjunctionwith the carriage slides past the rack of the sleeve during this upwardmotion. A spring is positioned between the pawls, which causes the pawlsto engage onto their respective racks. On downward travel of the innersleeve, a pawl is engaged to the rack of the sleeve and a pawl slidespast the inner sleeve. The alternative action causes the carriage totravel upwards. When using traction to lengthen, both pawls will slideover the thread profile of the drive screw and past the racks of thesleeve and inner sleeve. This configuration allows the carriage totravel upward.

In one embodiment, the spinal correction apparatus includes a drivesystem that uses a worm drive and a pawl mechanism to raise and lowerthe carriage. Axial rotation of the worm drive causes a drive screw torotate about its axis, for example, about 90 degrees relative to theworm gear axis, via their engaged teeth, which follows the thread pitchof the drive screw and in turn forces the carriage to translate eitherup or down depending on the rotation of the worm drive. A plunger andcoil spring are positioned between a helical pawl and a housing, whichcauses the helical pawl to engage the drive screw thread. When the drivescrew is rotated, the helical pawl is forced to follow the thread pitchof the drive screw. Upward and downward motion is transmitted throughthe helical pawl to the carriage. For example, after implantation, apatient is periodically placed in traction in an effort to lengthen therod and compensate for patient growth. The rod automatically lengthensduring patient activity. If lengthening cannot be achieved by placingthe patient in traction, fluoroscopy can be used to locate the drive hexand a driver is percutaneously docked and rotated to lengthen theconstruct. Rotating the drive mechanism in one direction will lengthenthe rod and rotating the drive mechanism in the other direction willshorten the rod.

In one embodiment, the spinal correction apparatus lengthens using onlytraction and the system may extend, for example, to about 100 mm. Theapparatus comprises an elliptical body with dimensions including but notlimited to about 12 mm by about 9.5 mm. The system may also comprise aspring-loaded plunger.

In one embodiment, the spinal correction apparatus lengthens using onlya drive mechanism; for example, a drive hex. The apparatus may extendincluding but not limited to about 100 mm. The apparatus may comprise anelliptical body with the dimensions including but not limited to about14 mm by about 8 mm.

It is contemplated that one or all of the components of the surgicalsystem may be disposable, peel-pack, pre-packed sterile devices. One orall of the components of the system may be reusable. The system may beconfigured as a kit with multiple sized and configured components.

It is envisioned that the present disclosure may be employed to treatspinal disorders such as, for example, degenerative disc disease, discherniation, osteoporosis, spondylolisthesis, stenosis, scoliosis andother curvature abnormalities, kyphosis, tumor and fractures. It iscontemplated that the present disclosure may be employed with otherosteal and bone related applications, including those associated withdiagnostics and therapeutics. It is further contemplated that thedisclosed system may be alternatively employed in a surgical treatmentwith a patient in a prone or supine position, and/or employ varioussurgical approaches to the spine, including anterior, posterior,posterior mid-line, direct lateral, postero-lateral, and/orantero-lateral approaches, and in other body regions. The presentdisclosure may also be alternatively employed with procedures fortreating the lumbar, cervical, thoracic and pelvic regions of a spinalcolumn. The system and methods of the present disclosure may also beused on animals, bone models and other non-living substrates, such as,for example, in training, testing and demonstration.

The present disclosure may be understood more readily by reference tothe following detailed description of the disclosure taken in connectionwith the accompanying drawing figures, which form a part of thisdisclosure. It is to be understood that this disclosure is not limitedto the specific devices, methods, conditions or parameters describedand/or shown herein, and that the terminology used herein is for thepurpose of describing particular embodiments by way of example only andis not intended to be limiting of the claimed disclosure. Also, as usedin the specification and including the appended claims, the singularforms “a,” “an,” and “the” include the plural, and reference to aparticular numerical value includes at least that particular value,unless the context clearly dictates otherwise. Ranges may be expressedherein as from “about” or “approximately” one particular value and/or to“about” or “approximately” another particular value. When such a rangeis expressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. It isalso understood that all spatial references, such as, for example,horizontal, vertical, top, upper, lower, bottom, left and right, are forillustrative purposes only and can be varied within the scope of thedisclosure. For example, the references “upper” and “lower” are relativeand used only in the context to the other, and are not necessarily“superior” and “inferior”.

Further, as used in the specification and including the appended claims,“treating” or “treatment” of a disease or condition refers to performinga procedure that may include administering one or more drugs to apatient (human, normal or otherwise or other mammal), in an effort toalleviate signs or symptoms of the disease or condition. Alleviation canoccur prior to signs or symptoms of the disease or condition appearing,as well as after their appearance. Thus, treating or treatment includespreventing or prevention of disease or undesirable condition (e.g.,preventing the disease from occurring in a patient, who may bepredisposed to the disease but has not yet been diagnosed as having it).In addition, treating or treatment does not require complete alleviationof signs or symptoms, does not require a cure, and specifically includesprocedures that have only a marginal effect on the patient. Treatmentcan include inhibiting the disease, e.g., arresting its development, orrelieving the disease, e.g., causing regression of the disease. Forexample, treatment can include reducing acute or chronic inflammation;alleviating pain and mitigating and inducing re-growth of new ligament,bone and other tissues; as an adjunct in surgery; and/or any repairprocedure. Also, as used in the specification and including the appendedclaims, the term “tissue” includes soft tissue, ligaments, tendons,cartilage and/or bone unless specifically referred to otherwise.

The following discussion includes a description of a surgical system andrelated methods of employing the surgical system in accordance with theprinciples of the present disclosure. Alternate embodiments are alsodisclosed. Reference will now be made in detail to the exemplaryembodiments of the present disclosure, which are illustrated in theaccompanying figures. Referring now to FIGS. 1-13, there is illustratedcomponents of a surgical system including, for example, a spinalcorrection apparatus 40 in accordance with the principles of the presentdisclosure.

The components of the surgical system can be fabricated frombiologically acceptable materials suitable for medical applications,including metals, synthetic polymers, ceramics, bone material, tissueand/or their composites, depending on the particular application and/orpreference of a medical practitioner. For example, the components of thesurgical system, individually or collectively, can be fabricated frommaterials such as stainless steel alloys, commercially pure titanium,titanium alloys, Grade 5 titanium, super-elastic titanium alloys,cobalt-chrome alloys, stainless steel alloys, superelastic metallicalloys (e.g., Nitinol, super elasto-plastic metals, such as GUM METAL®manufactured by Toyota Material Incorporated of Japan), ceramics andcomposites thereof such as calcium phosphate (e.g., SKELITE™manufactured by Biologix Inc.), thermoplastics such aspolyaryletherketone (PAEK) including polyetheretherketone (PEEK),polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEKcomposites, PEEK-BaSO₄ polymeric rubbers, polyethylene terephthalate(PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers,polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigidmaterials, elastomers, rubbers, thermoplastic elastomers, thermosetelastomers, elastomeric composites, rigid polymers includingpolyphenylene, polyamide, polyimide, polyetherimide, polyethylene,epoxy, bone material including autograft, allograft, xenograft ortransgenic cortical and/or corticocancellous bone, and tissue growth ordifferentiation factors, partially resorbable materials, such as, forexample, composites of metals and calcium-based ceramics, composites ofPEEK and calcium based ceramics, composites of PEEK with resorbablepolymers, totally resorbable materials, such as, for example, calciumbased ceramics such as calcium phosphate, tri-calcium phosphate (TCP),hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymerssuch as polyaetide, polyglycolide, polytyrosine carbonate,polycaroplaetohe and their combinations. Various components of thesurgical system may have material composites, including the abovematerials, to achieve various desired characteristics such as strength,rigidity, elasticity, compliance, biomechanical performance, durabilityand radiolucency or imaging preference. The components of the surgicalsystem, individually or collectively, may also be fabricated from aheterogeneous material such as a combination of two or more of theabove-described materials. The components of the surgical system may bemonolithically formed, integrally connected or include fasteningelements and/or instruments, as described herein.

The components of the surgical system including spinal correctionapparatus 40 are employed, for example, with an open or mini-open,minimal access and/or minimally invasive including percutaneous surgicaltechnique to attach a longitudinal element to a spine that has a spinaldisorder. In one embodiment, the longitudinal element may be affixed toa selected section of the spine and/or other anatomy while allowing forgrowth and adjustments to a concave side of a plurality of vertebrae fora correction treatment to treat various spine pathologies, such as, forexample, adolescent idiopathic scoliosis and Scheuermann's kyphosis.

Spinal correction apparatus 40 includes a body, such as, for example,outer sleeve 42 that defines a longitudinal axis a. Outer sleeve 42extends between a first end 44 and a second end 46. Sleeve 42 has acylindrical cross sectional configuration. It is envisioned that sleeve42 may have an oval, oblong, triangular, square, polygonal, irregular,uniform, non-uniform, offset, staggered, undulating, arcuate, variableand/or tapered configuration. Sleeve 42 includes an outer surface 48. Itis contemplated that all or only a portion of outer surface 48 may havealternate surface configurations to enhance fixation with tissue suchas, for example, rough, arcuate, undulating, mesh, porous, semi-porous,dimpled and/or textured according to the requirements of a particularapplication. Sleeve 42 includes an inner surface 50 that defines acavity 52. Cavity 52 has an oval cross sectional configuration. It isenvisioned that cavity 52 may have alternate cross sectionalconfigurations such as, for example, oblong, triangular, square,polygonal, irregular, uniform, non-uniform, offset, staggered,undulating, arcuate, variable and/or tapered configuration. Cavity 52 isconfigured for disposal of the components of spinal correction apparatus40. It is envisioned that sleeve 42 may include an opening for observingthe components located within sleeve 42.

End cap 54 is disposed at first end 44 of sleeve 42 and includes acentrally located opening 56. Opening 56 is configured for movabledisposal of a first longitudinal element, such as, for example, a rod120, discussed below. End cap 58 is disposed at second end 46 of sleeve42 and includes a centrally located opening 60. Opening 60 is configuredfor disposal of a second longitudinal element, such as, for example, arod 122, discussed below. It is envisioned that openings 56, 60 may havealternate cross sectional configurations such as, for example, circular,oval, oblong, triangular, square, polygonal, irregular, uniform,non-uniform, offset, staggered, undulating, arcuate, variable and/ortapered configuration.

A ratchet 62 is connected to sleeve 42. Ratchet 62 is disposed withincavity 52 of sleeve 42. Ratchet 62 includes a rack 64 mounted to innersurface 50. Rack 64 extends between a first end 66 and a second end 68.First end 66 includes a connecting portion, such as, for exampletransverse flange 70. Flange 70 has an opening configured for supportand slidable movement of rod 120. Flange 70 is mounted adjacent end 44with end cap 54. Rack 64 includes gear teeth 72 disposed axially betweenends 66, 68.

Ratchet 62 includes a second rack 74 formed within inner surface 50.Second rack 74 extends between a first end and a second end. Second rack74 includes gear teeth 80 disposed axially along inner surface 50. It iscontemplated that rack 74 may be a separate component and mounted toinner surface 50.

Ratchet 62 includes a carriage assembly comprising a carriage 82.Carriage 82 defines surface 84 that defines a cavity for disposal ofpawls 88, 90. Pawl 88 includes gear teeth 92. Gear teeth 92 areconfigured for engagement with gear teeth 80 of second rack 74. Pawl 90includes gear teeth 94. Gear teeth 94 are configured for engagement withgear teeth 72 of first rack 64. Pin 96 connects pawls 88, 90 to carriage82.

Pawls 88, 90 are rotatable relative to carriage 82 such that pawls 88,90 pivot about pin 96 respectively. Pawl 88 pivots about pin 96 tofacilitate releasable engagement of teeth 92 with teeth 80 and pawl 90pivots about pin 96 to facilitate releasable engagement of teeth 72 withteeth 94 to advance carriage 82 in at least one axial direction. It iscontemplated that a biasing member may be connected to pawls 88, 90 tofacilitate pivotable movement of pawls 88, 90 relative to carriage 82.In one embodiment, the biasing member includes a spring.

Second end 68 includes a housing 100. Housing 100 includes an innersurface 102 that defines a transverse channel 104. Channel 104 has anon-circular configuration, such as, for example, substantiallyelliptical for movable disposal of an actuator 106. Channel 104 may havevarious configurations, such as, for example, those alternativesdescribed herein.

Actuator 106 includes a cam 108. Cam 108 has an outer surface 110 and acylindrical configuration. Cam 108 is rotatable within channel 104 suchthat outer surface 110 engages inner surface 102 to cause axialtranslation of housing 100. Cam 108 includes a socket 112 having ahexagonal configuration. Socket 112 is configured for engagement with aninstrument, as described below. Socket 112 is offset from a centraltransverse axis of cam 108 such that cam 108 is rotatable to follow anoff center transverse axis path relative to the central transverse axis.Actuator 106 includes washer 114 that includes an inner surface 116.Washer 114 is disposed with cam 108, which are mounted with opening 118of sleeve 42.

Actuator 106 is disposed with sleeve 42 and is connected to ratchet 62to facilitate incremental movement of rod 120 relative to sleeve 42 inat least one axial direction. Actuator 106 is rotatable in a firstdirection, such as, for example, a clockwise direction and a seconddirection, such as, for example, a counter clockwise direction in orderto facilitate movement of rod 120 in at least one axial direction, suchas, for example, a first axial direction, as shown by arrow B in FIG. 3.

Rod 120 extends between a first end 124 and a second end 126 (FIG. 8).Rod 120 is inserted into sleeve 42 through opening 56 of end cap 54. Rod120 is disposed in a telescopic configuration within sleeve 42. Secondend 126 includes an outer surface that is threaded with a threadedcavity 127 (FIG. 8) of carriage 82 to facilitate movement of rod 120relative to sleeve 42, as will be described.

Spinal correction apparatus 40 includes a second longitudinal element,such as for example, rod 122. Rod 122 extends between a first end 128and a second end 129 (FIG. 8). Rod 122 is inserted into sleeve 42through opening 60 of end cap 58.

Rods 120, 122 can have a uniform thickness/diameter. It is envisionedthat rods 120, 122 may have various surface configurations, such as, forexample, rough, threaded for connection with surgical instruments,arcuate, undulating, dimpled, polished and/or textured according to therequirements of a particular application. It is contemplated that thethickness defined by rods 120, 122 may be uniformly increasing ordecreasing, or have alternate diameter dimensions along their length. Itis further contemplated that rods 120, 122 may have various crosssection configurations, such as, for example, oval, oblong, triangular,rectangular, square, polygonal, irregular, uniform, non-uniform,variable and/or tapered. It is contemplated that rods 120, 122 may havevarious lengths, according to the requirements of a particularapplication.

In operation, as shown in FIGS. 4-10, the system including spinalcorrection apparatus 40 includes an instrument, such as, for example, adrive tool 132, as shown in FIGS. 4-6. Drive tool 132 is manipulated toengage cam 108 of actuator 106 and rotated to facilitate incrementalmovement of rod 120 relative to sleeve 42 in at least one axialdirection. Drive tool 132 includes a tip 134 having a hexagonal crosssection configuration for mating with socket 112. It is contemplatedthat tip 134 may have alternative configurations, such as, for example,those alternatives described herein.

Tip 134 is inserted into opening 118 of sleeve 42 and passes throughinner surface 116 of washer 114, as shown in FIGS. 7-8. Cam 108 isdisposed in a first orientation in channel 104. Carriage 82 is disposedadjacent second end 46 and pawls 88, 90 are disposed to engage racks 74,64, respectively, in a gear mesh fixation.

Tip 134 is caused to engage socket 112 of cam 108 and drive tool 132 isrotated in a clockwise direction, as shown by arrow A in FIG. 7. Drivetool 132 rotates cam 108 within channel 104 such that the circularconfiguration of outer surface 110 engages the non-circularconfiguration of inner surface 102 along an off center path of rotation.Engagement of outer surface 110 with inner surface 102 drives housing100 towards first end 44 and into engagement with carriage 82. Carriage82 is driven in the first axial direction, as shown by arrow B, towardsfirst end 44 such that teeth 92 advance along teeth 80 and teeth 94advance along teeth 72. Pawls 88, 90 are biased outwardly such that thegear teeth are disposed in a releasable mesh fixation and a fixedposition with racks 74, 64.

As carriage 82 advances in the direction of arrow B, pawls 88, 90 becomereleasably fixed in an advanced position with racks 74, 64 such that therespective rack and pawl teeth are engaged, as shown in FIGS. 9-10. Asdrive tool 132 is further rotated, carriage 82 is further advanced inthe direction shown by arrow B, via advancement of pawls 88, 90 withracks 74, 64 as described, and rod 120 is advanced in the directionshown by arrow B, according to the requirements of a particularapplication. This configuration facilitates incremental movement of rod120 relative to sleeve 42 in the direction shown by arrow B. Movement ofrod 120 relative to sleeve 42 expands the overall length of apparatus 40to be used, for example, with a body invasive procedure forstabilization of vertebrae, initial implantation and/or to compensatefor patient growth. In one embodiment, cam 108 may be rotated in aclockwise direction and a counterclockwise direction to advance rod 120in the first axial direction. In one embodiment, rod 120 is advanced inthe first axial direction only. In one embodiment, movement of rod 120relative to sleeve 42 expands the overall length of spinal correctionapparatus to compensate for axial rotation of a body.

Spinal correction apparatus 40 is also configured for non-invasivelengthening to compensate for patient growth, as shown in FIGS. 11-13.For example, during patient growth, a force, such as, for example, anexpansion force, due to separation of anatomical body portions attachedto apparatus 40, is applied to rod 120 and/or rod 122 that causesdynamic incremental movement of rod 120, independent of actuator 106,relative to sleeve 42 in the first axial direction, as shown by arrow Bin FIG. 11. In one embodiment, dynamic incremental movement of rod 120and/or rod 122 is responsive to, caused by and/or associated with motionof a spine and adjacent anatomical portions of a body of a patient. Inone embodiment, such motion includes motion of the spine and adjacentanatomical portions due to the natural load bearing and dynamiccharacteristics of the spine, which may include flexion, extension,rotation and lateral bending. In one embodiment, such motion includesmotion of the spine and adjacent anatomical portions due to externalloads, which may include axial, shear, linear, non-linear, angular,torsional, compressive and/or tensile loads, applied to the body of thepatient.

Upon application of the expansion force to first end 124 of rod 120,carriage 82 is drawn in the first axial direction, as shown by arrow B,towards first end 44 such that teeth 92 advance along teeth 80 and teeth94 advance along teeth 72, as shown in FIGS. 12-13. Pawls 88, 90 arebiased outwardly such that the gear teeth are disposed in a releasablemesh fixation and a fixed position with racks 74, 64. In one embodiment,the forces are applied to rod 122.

As carriage 82 is drawn and advances in the direction of arrow B, pawls88, 90 become releasably fixed in an advanced position with racks 74, 64such that the respective rack and pawl teeth are disposed in areleasable mesh fixation. Carriage 82 is advanced in the direction shownby arrow B, via advancement of pawls 88, 90 with racks 74, 64 asdescribed, and rod 120 is advanced in the direction shown by arrow B,according to the expansion force, such as, for example, an amount ofgrowth between the anatomical portions connected to spinal correctionapparatus 40. The mesh engagement of the gear teeth of pawls 88, 90 withracks 74, 64 prevents contraction and/or axial movement of rod 120relative to sleeve 42 in a direction opposite to the first axialdirection and permits further expansion and/or advancement of rod 120relative to sleeve 42, in the first axial direction, according to otherforces applied to spinal correction apparatus 40 and/or subsequentpatient growth. This configuration provides dynamic incremental movementof rod 120 relative to sleeve 42 in the direction shown by arrow B, tobe used, for example, for stabilization of vertebrae and non-invasivelengthening and/or compensation for patient growth.

In assembly, operation and use, a system including spinal correctionapparatus 40, similar to that described above, is employed with asurgical procedure, such as, for example, a correction treatment totreat adolescent idiopathic scoliosis and/or Scheuermann's kyphosis of aspine. It is contemplated that one or all of the components of thespinal correction system can be delivered or implanted as apre-assembled device or can be assembled in situ. The system includingspinal correction apparatus 40 may be completely or partially revised,removed or replaced.

For example, spinal correction apparatus 40, described above, can beemployed with a surgical correction treatment of an applicable conditionor injury of an affected section of a spinal column and adjacent areaswithin a body, such as, for example, at least a first vertebra V1 and asecond vertebra V2 of vertebrae V. It is envisioned that spinalcorrection apparatus 40 may be employed with one or a plurality ofvertebrae.

In use, to treat a selected section of vertebrae V, a medicalpractitioner obtains access to a surgical site including vertebrae V inany appropriate manner, such as through incision and retraction oftissues. It is envisioned that the spinal correction system can be usedin any existing surgical method or technique including open surgery,mini-open surgery, minimally invasive surgery and percutaneous surgicalimplantation, whereby vertebrae V is accessed through a mini-incision,or sleeve that provides a protected passageway to the area. Once accessto the surgical site is obtained, the particular surgical procedure canbe performed for treating the spine disorder.

An incision is made in the body of a patient and a cutting instrument(not shown) creates a surgical pathway for implantation of components ofthe system including spinal correction apparatus 40. A preparationinstrument (not shown) can be employed to prepare tissue surfaces ofvertebrae V, as well as for aspiration and irrigation of a surgicalregion according to the requirements of a particular surgicalapplication.

Referring to FIGS. 14 and 15, a first fastening element, such as, forexample, fixation screw assembly 152 is configured to attach first end124 of rod 120 to vertebra V1. A second fastening element, such as, forexample, fixation screw assembly 154 is configured to attach first end128 of rod 122 to vertebra V2, which is spaced apart over vertebrae fromvertebra V1. Pilot holes are made in vertebrae V1, V2 for receivingfixation screw assemblies 152, 154. Fixation screw assemblies 152, 154include threaded bone engaging portions that are inserted or otherwiseconnected to vertebrae V1, V2, according to the particular requirementsof the surgical treatment. Fixation screw assemblies 152, 154 each havea head 156 with a bore, or through opening and a setscrew 158, which istorqued on to ends 124, 128 to attach spinal correction apparatus 40 inplace with vertebrae V, as will be described. It is envisioned that thefastening elements may include one or a plurality of hooks, anchors,tissue penetrating screws, mono-axial screws, multi-axial screws,expanding screws, wedges, buttons, clips, snaps, friction fittings,compressive fittings, expanding rivets, staples, nails, adhesives,fixation plates and/or posts. These fixation elements may be coated withan osteoinductive or osteoconductive material to enhance fixation,and/or include one or a plurality of therapeutic agents.

Upon fixation of spinal correction apparatus 40 with vertebrae V, asdescribed, drive tool 132 is manipulated to engage cam 108 of actuator106 and rotated to facilitate incremental movement of rod 120 relativeto sleeve 42 in a first axial direction, as shown by arrow B in FIG. 15and described above. Carriage 82 is advanced in the first axialdirection such that pawls 88, 90 become releasably fixed in an advancedposition with racks 74, 64 such that the respective rack and pawl teethare engaged. Drive tool 132 is rotated to advance carriage 82 and expandrod 120 in the first axial direction, according to the requirements of aparticular application. This configuration facilitates incrementalmovement of rod 120 relative to sleeve 42 in the first axial direction.Movement of rod 120 relative to sleeve 42 expands the overall length ofspinal correction apparatus 40 for initial implantation andstabilization of vertebrae for a particular procedure. Upon completionof the procedure, the surgical instruments and assemblies are removedand the incision is closed. It is contemplated that spinal correctionapparatus 40 may be adjusted in subsequent procedures with drive tool132 engaging cam 108.

Upon implantation of spinal correction apparatus 40 and completion ofthe procedure, spinal correction apparatus 40 is configured for in situ,non-invasive lengthening to compensate for patient growth. For example,during patient growth, an expansion force, due to separation ofvertebrae V1, V2 attached to spinal correction apparatus 40, is appliedto rod 120 and/or rod 122 that causes dynamic incremental movement ofrod 120, independent of actuator 106, relative to sleeve 42 in the firstaxial direction, as shown by arrow B in FIG. 15 and described above.

Upon application of the expansion force to first end 124 of rod 120,carriage 82 is drawn in the first axial direction and advances such thatpawls 88, 90 become releasably fixed in an advanced position with racks74, 64. The mesh engagement of the gear teeth of pawls 88, 90 with racks74, 64 prevents contraction and/or axial movement of rod 120 relative tosleeve 42 in a direction opposite to the first axial direction andpermits further expansion and/or advancement of rod 120 relative tosleeve 42, in the first axial direction, according to other forcesapplied to spinal correction apparatus 40 and/or subsequent patientgrowth. This configuration provides dynamic incremental movement of rod120 relative to sleeve 42 in the first axial direction.

In one embodiment, ends 124, 128 can be attached from a selected portionof the spine to a selected portion of the ribs. In one embodiment, ends124, 128 may be attached from the pelvic crest to a selected portion ofthe cervical spine. In one embodiment, ends 124, 128 can be attachedfrom the pelvic crest to a selected portion of the ribs.

The system including spinal correction apparatus 40 can be made ofradiolucent materials such as polymers. Radiomarkers may be included foridentification under x-ray, fluoroscopy, CT or other imaging techniques.It is envisioned that the use of microsurgical and image guidedtechnologies may be employed to access, view and repair spinaldeterioration or damage, with the aid of the system including spinalcorrection apparatus 40.

It is contemplated that the components of the system including spinalcorrection apparatus 40 may be employed to treat progressive idiopathicscoliosis with or without sagittal deformity in either infantile orjuvenile patients, including but not limited to prepubescent children,adolescents from 10-12 years old with continued growth potential, and/orolder children whose growth spurt is late or who otherwise retain growthpotential. It is further contemplated that the components of the systemincluding spinal correction apparatus 40 and method of use may be usedto prevent or minimize curve progression in individuals of various ages.

In one embodiment, as shown in FIGS. 16-29, the system comprising spinalcorrection apparatus 40, similar to the apparatus and methods describedabove with regard to FIGS. 1-15, includes a body, such as, for example,outer sleeve 242 that defines a longitudinal axis b. Outer sleeve 242extends between a first end 244 and a second end 246. Sleeve 242 has acylindrical cross sectional configuration and an outer surface 248.Sleeve 242 includes an inner surface 250 that defines a cavity 252.Cavity 252 has an oval cross section configuration. Cavity 252 isconfigured for disposal of the components of spinal correction apparatus40.

End cap 254 is disposed at first end 244 of sleeve 242 and includesoffset opening 256. Opening 256 is configured for movable disposal of afirst longitudinal element, such as, for example, a rod 320, discussedbelow. End cap 258 is disposed at second end 246 of sleeve 242 andincludes a centrally located opening 260. Opening 260 is configured fordisposal of a second longitudinal element, such as, for example, a rod322, discussed below.

A bushing 338 is threadingly disposed within end cap 254. Bushing 338includes a centrally located opening 340. Opening 340 has a threadedexterior surface 342 for mounting with end cap 254. Bushing 338 isconfigured for movable disposal of rod 320.

A ratchet 262 is connected to sleeve 242. Ratchet 262 is disposed withincavity 252 of sleeve 242. Ratchet 262 includes a rack, such as, forexample, a drive screw 264 mounted to inner surface 250. Drive screw 264extends between a first end 266 and a second end 268. Drive screw 264includes a thread form 272 disposed axially between ends 266 and 268.Thread form 272 has a pitch that causes axial movement of a carriageassembly therealong, discussed below.

Ratchet 262 includes the carriage assembly comprising a carriage 282.Carriage 282 includes surfaces 284, 286 that define cavities for supportof at least one post, discussed below, which movably connects a pawl290, described below, with carriage 282. Carriage 282 includes a cavity344 that has a threaded surface 346. Cavity 344 is configured fordisposal of rod 320 and threaded surface 346 engages second end 326 forfixation therewith.

Carriage 282 includes gear teeth 348 configured for engagement withdrive screw 264. Gear teeth 348 movably engage thread form 272 for axialmovement in at least one axial direction relative to sleeve 242 alongthe helical and/or spiral configuration of thread form 272. A thrustwasher 350 is configured for disposal within end cap 258. Thrust washer350 includes opening 352 configured for movable disposal of drive screwsecond end 268.

Pawl 290 includes gear teeth 294 configured for engagement with threadform 272. A pin 298 extends through cavity 284 and pawl 290 to connectpawl 290 to carriage 282. Pawl 290 is pivotable relative to carriage282. Pawl 290 rotates relative to carriage 282 such that pawl 290 pivotsabout pin 298. Pawl 290 pivots about pin 298 to facilitate releasableengagement of teeth 294 with thread form 272.

Pawl 290 includes a transverse recess 354 configured for disposal of aplunger 356 and a spring 358. Plunger 356 and spring 358 are disposedwithin transverse recess 354 to facilitate biased movement of pawl 290into engagement with thread form 272. Spring 358 biases plunger 356against the wall of sleeve 242 such that pawl pivots about pin 298 andgear teeth 294 are forced into a releasable mesh fixation and a fixedposition with thread form 272.

Actuator 306 includes worm gear 308. Worm gear 308 has an outer threadedsurface 310. Worm gear 308 is rotatable within a channel 360 of an endcap 258 such that outer threaded surface 310 engages with gear teeth 362at an enlarged second end 268 of drive screw 264. End cap 258 defines acavity that supports carriage 282 and drive screw 264. Worm gear 308includes socket 312 having a hexagonal configuration. Socket 312 isconfigured for engagement with an instrument, as described below.Actuator 306 includes washer 314 having an opening 316. Washer 314 isdisposed with worm gear 308, which are both mounted within channel 360of end cap 258.

Actuator 306 is disposed within channel 360 and is connected to ratchet262 to facilitate incremental movement of rod 320 relative to sleeve 242in at least one axial direction. Actuator 306 is rotatable in a firstdirection, such as, for example, a clockwise direction and a seconddirection, such as, for example, a counter clockwise direction tofacilitate movement of rod 320 in at least one axial direction, such as,for example, a first axial direction, as shown by arrow B′ in FIG. 18.

Rod 320 extends between a first end 324 and a second threaded end 326.Rod 320 is inserted into sleeve 242 through bushing 338 and end cap 254.Second end 326 is fixed with carriage 282 in a threaded engagement. Rod320 is disposed in a telescopic configuration within sleeve 242. Spinalcorrection apparatus 40 includes a second longitudinal element, such as,for example, rod 322. Rod 322 extends between a first end 328 and asecond end (not shown). Rod 322 is inserted into sleeve 242 through endcap 258.

In operation, as shown in FIGS. 19-29, the system including spinalcorrection apparatus 40 includes an instrument, such as, for example, adrive tool 332. Drive tool 332 is manipulated to engage worm gear 308and rotated to facilitate incremental movement of rod 320 relative tosleeve 242 in at least one axial direction. Drive tool 332 includes atip 334 having a hexagonal cross section configuration for mating withsocket 312.

Tip 334 is inserted into opening 318 of end cap 258 and passes throughopening 316 of washer 314, as shown in FIGS. 19-20. Worm gear 308 isdisposed in a first orientation with gear teeth 362 of enlarged secondend 268 within end cap 258. Carriage 282 is disposed adjacent second end246 and pawl 290 is disposed to engage thread form 272 in a gear meshfixation.

Tip 334 is caused to engage socket 312 of worm gear 308 and drive tool332 is rotated in a clockwise direction, as shown by arrow A1 in FIGS.22 and 24. Drive tool 332 rotates worm gear 308 such that threadedsurface 310 engages gear teeth 362 of second end 268 to rotate drivescrew 264 in a first direction, such as, for example, a counterclockwisedirection, as shown by arrow E in FIG. 24. Thread form 272 engages gearteeth 294 of pawl 290 along its helical configuration. Carriage 282 isdriven in the first axial direction, as shown by arrow B′, towards firstend 244 such that teeth 294 advance axially in the first axial directionalong the helical configuration of thread form 272. Pawl 290 is biasedinto engagement with thread form 272 to maintain engagementtherebetween.

As drive tool 332 is further rotated, carriage 282 is further advanced,according to the requirements of a particular application. Thisconfiguration facilitates incremental movement of rod 320 relative tosleeve 242 in the first axial direction. Movement of rod 320 relative tosleeve 242 expands the overall length of apparatus 40 to be used, forexample, with a body invasive procedure for stabilization of vertebrae,initial implantation and/or to compensate for patient growth.

Spinal correction apparatus 40 can be contracted such that tip 334 iscaused to engage socket 312 of worm gear 308 and drive tool 332 isrotated in a counterclockwise direction, as shown by arrow A2 in FIGS.21 and 23. Drive tool 332 rotates worm gear 308 such that threadedsurface 310 engages gear teeth 362 of second end 268 to rotate drivescrew 264 in a second direction, such as, for example, a clockwisedirection, as shown by arrow D in FIG. 23. Thread form 272 engages gearteeth 294 of pawl 290 along its helical configuration. Carriage 282 isdriven in a second axial direction, as shown by arrow C′, towards secondend 246 such that teeth 294 advance axially in the second axialdirection along the helical configuration of thread form 272. Pawl 290is biased into engagement with thread form 272 to maintain engagementtherebetween. This configuration facilitates incremental movement of rod320 relative to sleeve 242 in the second axial direction to compressand/or contract the overall length of spinal correction apparatus 40. Inone embodiment, rod 320 is advanced in the first axial direction only orin the second axial direction only. In one embodiment, movement of rod320 relative to sleeve 242 expands the overall length of apparatus 40 tocompensate for axial rotation of a body.

Spinal correction apparatus 40 is also configured for non-invasivelengthening to compensate for patient growth, as shown in FIGS. 26-29.For example, during patient growth, a force, such as, for example, anexpansion force, due to separation of anatomical body portions attachedto spinal correction apparatus 40, is applied to rod 320 and/or rod 322that causes dynamic incremental movement of rod 320, independent ofactuator 306, relative to sleeve 242 in the first axial direction, asshown by arrow B′ in FIG. 26, similar to that described above withregard to FIGS. 11-13.

Upon application of the expansion force to first end 324 of rod 320,carriage 282 is drawn in the first axial direction towards first end 244such that teeth 294 advance axially in the first axial direction alongthe helical configuration of thread form 272 such that teeth 294 slideover thread form 272, as shown in FIGS. 12-13. Pawl 290 is biased intoengagement with thread form 272. In one embodiment, the forces areapplied to rod 322.

Carriage 282 is advanced in the direction shown by arrow B′ in FIG. 26and teeth 294 slide over thread form 272, according to the expansionforce, such as, for example, an amount of growth between the anatomicalportions connected to spinal correction apparatus 40. Upon reaching anequilibrium with the expansion force, teeth 294 are disposed in a meshengagement with thread form 272, as facilitated by the bias of pawl 290with thread form 272. This configuration prevents contraction and/oraxial movement of rod 320 relative to sleeve 242 in a direction oppositeto the first axial direction and permits further expansion and/oradvancement of rod 320 relative to sleeve 242, in the first axialdirection, according to other forces applied to spinal correctionapparatus 40 and/or subsequent patient growth. This configurationprovides dynamic incremental movement of rod 320 relative to sleeve 242in the direction shown by arrow B′ in FIG. 26, to be used, for example,for stabilization of vertebrae and non-invasive lengthening and/orcompensation for patient growth.

In one embodiment, as shown in FIGS. 30-31, the system comprising spinalcorrection apparatus 40, similar to the apparatus and methods describedabove with regard to FIGS. 16-29, includes a body, such as, for example,outer sleeve 442 that defines a longitudinal axis c. Outer sleeve 242extends between a first end 444 and a second end 446. Sleeve 442 has anelliptical cross section configuration. Sleeve 442 includes an outersurface 448. Sleeve 442 includes an inner surface 450 that defines acavity 452. Cavity 252 is configured for disposal of the components ofspinal correction apparatus 40.

First end 444 is configured for movable disposal of a first longitudinalelement, such as, for example, a rod 520. Second end 446 is configuredfor disposal of a second longitudinal element, such as, for example, arod 522.

A ratchet 462 is connected to sleeve 442. Ratchet 462 is disposed withincavity 452 of sleeve 442. Ratchet 462 includes a rack 464 mounted toinner surface 450. Rack 464 includes gear teeth 472 disposed axiallytherealong.

Ratchet 462 includes a carriage assembly comprising a carriage 482.Carriage 482 includes a surface that defines a cavity 484 for support ofa pin 498, which movably connects a pawl 490, described below, withcarriage 482. Carriage 482 includes a cavity 544 that has a threadedsurface 546. Cavity 544 is configured for disposal of rod 520 andthreaded surface 546 engages the second end of rod 520 for fixationtherewith. Pawl 490 includes gear teeth 494 configured for engagementwith gear teeth 472. Pin 498 extends through cavity 484 and pawl 490 toconnect pawl 490 to carriage 482. Pawl 490 is pivotable relative tocarriage 482. Pawl 490 rotates relative to carriage 482 such that pawl490 pivots about pin 498. Pawl 490 pivots about pin 498 to facilitatereleasable engagement of teeth 494 with gear teeth 472.

Pawl 490 includes a transverse recess 554 configured for disposal of aplunger 556 and a spring 558. Plunger 556 and spring 558 are disposedwithin transverse recess 554 to facilitate biased movement of pawl 490into engagement with gear teeth 472. Spring 558 biases plunger 556against the wall of sleeve 442 such that pawl 490 pivots about pin 498and gear teeth 494 are forced into a releasable mesh fixation and afixed position with gear teeth 472.

Rod 520 extends between a first end 524 and a second threaded end 526.Rod 520 is inserted into sleeve 442 through first end 524. Second end526 is fixed with carriage 482 in a threaded engagement. Rod 520 isdisposed in a telescopic configuration within sleeve 442. Spinalcorrection apparatus 40 includes a second longitudinal element, such as,for example, rod 522. Rod 522 extends between a first end 528 and asecond end (not shown). Rod 522 is inserted into sleeve 542 throughsecond end 446.

In operation, spinal correction apparatus 40 is configured fornon-invasive lengthening to compensate for patient growth, as shown inFIGS. 30-31. For example, during patient growth, a force, such as, forexample, an expansion force, due to separation of anatomical bodyportions attached to spinal correction apparatus 40, is applied to rod520 and/or rod 522 that causes dynamic incremental movement of rod 520relative to sleeve 542 in a first axial direction, similar to thatdescribed above with regard to FIGS. 16-29.

Upon application of the expansion force to first end 524 of rod 520,carriage 482 is drawn in the first axial direction towards first end 444such that teeth 494 advance axially in the first axial direction alonggear teeth 472 such that teeth 494 slide over gear teeth 472. Pawl 490is biased into engagement with gear teeth 472 via spring 558/plunger556, described above. In one embodiment, the forces are applied to rod522.

Carriage 482 is advanced in the first axial direction and teeth 294slide over gear teeth 472, according to the expansion force, such as,for example, an amount of growth between the anatomical portionsconnected to spinal correction apparatus 40. Upon reaching anequilibrium with the expansion force, a mesh engagement of teeth 494with gear teeth 472, as facilitated by the bias of pawl 490 with gearteeth 472, prevents contraction and/or axial movement of rod 520relative to sleeve 442 in a direction opposite to the first axialdirection and permits further expansion and/or advancement of rod 520relative to sleeve 442, in the first axial direction, according to otherforces applied to spinal correction apparatus 40 and/or subsequentpatient growth. This configuration provides dynamic incremental movementof rod 520 relative to sleeve 542 in the first axial direction to beused, for example, for stabilization of vertebrae and non-invasivecompensation for patient growth.

In one embodiment, as shown in FIGS. 32-33, the system comprising spinalcorrection apparatus 40, similar to the apparatus and methods describedabove with regard to FIGS. 16-29, includes a body, such as, for example,outer sleeve 642 that defines a longitudinal axis d. Outer sleeve 642extends between a first end 644 and a second end 646. Sleeve 642includes an outer surface 648. Sleeve 642 includes an inner surface (notshown) that defines a cavity configured for disposal of the componentsof spinal correction apparatus 40.

An end cap 654 is disposed at first end 644 of sleeve 642 and includesan opening configured for movable disposal of a first longitudinalelement, such as, for example, a rod 720, discussed below. An end cap658 is disposed at second end 646 of sleeve 642 and includes an openingconfigured for disposal of a second longitudinal element, such as, forexample, a rod 722, discussed below.

A ratchet 662 is connected to sleeve 642. Ratchet 662 is disposed withinthe cavity of sleeve 642. Ratchet 662 includes a first rack, such as,for example, a drive screw 664 and a second rack, such as, for example,a drive screw 674. Drive screws 664, 674 are mounted to the innersurface of sleeve 642 and disposed axially in a substantially parallelorientation.

Drive screw 664 extends between a first end 666 and a second end 668.Drive screw 664 includes a thread form 672 disposed axially between ends666 and 668. Thread form 672 has a pitch that causes axial movement of acarriage assembly, discussed below. Drive screw 674 extends between afirst end 676 and a second end 678. Drive screw 674 includes a threadform 680 disposed axially between ends 676 and 678. Thread form 680 hasa pitch that causes axial movement of a carriage assembly, discussedbelow.

Ratchet 662 includes a carriage assembly comprising a carriage 682.Carriage 682 includes a first threaded cavity 770 and a second threadedcavity 772 that support drive screws 664, 674, respectively, andfacilitate axial translation of drive screws 664, 674 relative thereto,as will be described. Carriage 682 includes a threaded cavity 768configured for disposal of rod 720 and includes a threaded surface thatengages a threaded portion of second end 726 for fixation therewith.

Cavities 770, 772 include thread forms configured for engagement withdrive screws 664, 674. The thread forms of cavities 770, 772 movablyengage thread forms 672, 680 for axial movement in at least one axialdirection relative to sleeve 642 along the helical and/or spiralconfiguration of thread forms 672, 680.

An actuator 706 includes worm gear 708. Worm gear 708 has an outerthreaded surface 710. Worm gear 708 is rotatable within an end cap 658such that outer threaded surface 710 engages with gear teeth 762, 774 ofparallel gears disposed at second end 646. End cap 658 defines a cavitythat supports drive screws 664, 674. Worm gear 708 includes socket 712having a hexagonal configuration. Socket 712 is configured forengagement with an instrument, as described below.

Actuator 706 is connected to ratchet 262 to facilitate incrementalmovement of rod 720 relative to sleeve 642 in at least one axialdirection. Actuator 706 is rotatable in a first direction, such as, forexample, a clockwise direction and a second direction, such as, forexample, a counter clockwise direction to facilitate movement of rod 720in at least one axial direction, such as, for example, a first axialdirection, similar to that described above.

Rod 720 extends between a first end 724 and a second threaded end 726.Rod 720 is inserted into sleeve 642 through first end 644. Second end726 is fixed with carriage 682 in a threaded engagement. Rod 720 isdisposed in a telescopic configuration within sleeve 742. Spinalcorrection apparatus 40 includes a second longitudinal element, such as,for example, rod 722. Rod 722 extends between a first end 728 and asecond end 730. Rod 722 is inserted into sleeve 642 through second end646.

In operation, as shown in FIGS. 32-33, the system including spinalcorrection apparatus 40 includes an instrument, similar to thatdescribed above, which is manipulated to engage worm gear 708 androtated to facilitate incremental movement of rod 720 relative to sleeve642 in at least one axial direction. Carriage 682 is disposed adjacentsecond end 646.

Worm gear 708 is rotated in a clockwise direction such that threadedsurface 710 engages gear teeth 762, 774 to rotate drive screws 664, 674in a first direction. Thread forms 672, 680 engage the thread forms ofcavities 770, 772 along its respective helical configuration. Carriage682 is driven in the first axial direction towards first end 644 suchthat the thread forms of cavities 770, 772 advance axially in the firstaxial direction along the helical configuration of thread forms 672,680.

As the drive tool is further rotated, carriage 682 is further advanced,according to the requirements of a particular application. Thisconfiguration facilitates incremental movement of rod 720 relative tosleeve 642 in the first axial direction. Movement of rod 720 relative tosleeve 642 expands the overall length of apparatus 40 to be used, forexample, with a body invasive procedure for stabilization of vertebrae,initial implantation and/or to compensate for patient growth.

Spinal correction apparatus 40 can be contracted such that worm gear 708is rotated in a counterclockwise direction. The drive tool rotates wormgear 708 such that threaded surface 710 engages gear teeth 762, 774 torotate drive screws 664, 674 in a second direction. Thread forms 672,680 engage the thread forms of cavities 770, 772 along its respectivehelical configuration. Carriage 682 is driven in a second axialdirection towards second end 646 such that the thread forms of cavities770, 772 advance axially in the second axial direction along the helicalconfiguration of thread forms 672, 680. This configuration facilitatesincremental movement of rod 720 relative to sleeve 642 in the secondaxial direction to compress and/or contract the overall length of spinalcorrection apparatus 40.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplification of thevarious embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

1. A spinal correction apparatus comprising: a body; a ratchet disposedwith the body; and a longitudinal element connected to the ratchet,wherein a force applied to at least a portion of the apparatus causesdynamic incremental movement of the longitudinal element relative to thebody in at least one direction.
 2. An apparatus as recited in claim 1,further comprising an actuator disposed with the body and connected tothe ratchet to facilitate incremental movement of the longitudinalelement relative to the body in the at least one axial direction,wherein the force includes an expansion force applied to thelongitudinal element that causes the dynamic incremental movement of thelongitudinal element, independent of the actuator, relative to the bodyin a first axial direction. 3-6. (canceled)
 7. An apparatus as recitedin claim 1, wherein the longitudinal element is disposed in a telescopicconfiguration with the body.
 8. An apparatus as recited in claim 2,wherein the actuator is rotatable in at least one direction tofacilitate axial movement of the longitudinal element.
 9. An apparatusas recited in claim 2, wherein the actuator is rotatable in a firstdirection and a second direction to facilitate movement of thelongitudinal element in the first axial direction.
 10. (canceled)
 11. Anapparatus as recited in claim 2, wherein the actuator defines a socketconfigured for engagement with an instrument.
 12. An apparatus asrecited in claim 1, wherein the longitudinal element is connected withthe ratchet and configured for movement in a first axial direction only.13. An apparatus as recited in claim 1, wherein the longitudinal elementis connected with the ratchet and configured for movement in a firstaxial direction and a second axial direction.
 14. An apparatus asrecited in claim 1, wherein the longitudinal element is connected withthe ratchet and configured for movement in a first axial direction suchthat an overall length of the apparatus increases and a second axialdirection such that the overall length of the apparatus decreases. 15.An apparatus as recited in claim 1, wherein the ratchet comprises adrive screw and a carriage connected with the longitudinal element, thecarriage being engageable with the screw to facilitate axial movement ofthe longitudinal element.
 16. An apparatus as recited in claim 1,wherein the ratchet comprises a drive screw and a carriage connectedwith the longitudinal element, the ratchet further comprising a helicalpawl engageable with the carriage to facilitate axial movement of thelongitudinal element.
 17. An apparatus as recited in claim 2, whereinthe actuator includes a worm gear engageable with the ratchet.
 18. Anapparatus as recited in claim 2, wherein the actuator includes a wormgear engageable with the ratchet such that the longitudinal element ismovable in a first axial direction and a second axial direction. 19.(canceled)
 20. A spinal correction apparatus comprising: an outer sleeveextending between a first end and a second end, the outer sleeveincluding an inner surface that defines an elongated cavity; a ratchetdisposed with the cavity of the outer sleeve, the ratchet comprising adrive screw, a carriage and a helical pawl being engageable with thecarriage; a rod telescopically oriented with the outer sleeve andconnected to the carriage, the rod extending between a first end and asecond end; and a worm gear engageable with the screw in a configurationto facilitate incremental movement of the rod relative to the outersleeve in a first axial direction and a second axial direction, the wormgear defining a socket configured for engagement with an instrument,wherein an expansion force applied to the first end of the rod causesincremental movement of the rod, independent of the worm gear, relativeto the outer sleeve in the first axial direction.
 21. An apparatus asrecited in claim 1, wherein the longitudinal element comprises an outersurface that is threaded with a threaded cavity of the ratchet.
 22. Anapparatus as recited in claim 1, wherein the ratchet comprises a drivescrew and a carriage connected with the longitudinal element, the drivescrew being offset from a longitudinal axis defined by the longitudinalelement.
 23. An apparatus as recited in claim 1, wherein the ratchetcomprises a drive screw and a carriage connected with the longitudinalelement, the carriage being engageable with the drive screw tofacilitate axial movement of the longitudinal element.
 24. An apparatusas recited in claim 1, further comprising a second longitudinal elementthat is coaxial with the longitudinal element, the second longitudinalelement comprising a threaded outer surface that engages a threadedinner surface of the body.
 25. A spinal correction apparatus comprising:a sleeve extending between first and second ends, the sleeve includingan inner surface that defines a cavity; a ratchet disposed with thecavity and comprising a screw, a carriage and a pawl that is engageablewith the carriage; a rod telescopically oriented with the sleeve andconnected to the carriage; and a worm gear engageable with the screw ina configuration to facilitate incremental movement of the rod relativeto the sleeve in a first axial direction and a second axial direction.26. An apparatus as recited in claim 1, wherein screw is offset from alongitudinal axis defined by the rod.